In many areas of the world, environmental concerns have focused on industrial pollution, efforts to reduce such pollution, global warming, acid rain and protection of the ozone layer. It has also been recognized that waste combustible gases from industrial processes including petrochemical processes may contribute to harmful pollution. As a result, there have been numerous attempts to control emissions, namely in the form of flare gases.
One approach to control flare gas emissions is disclosed in a U.S. patent of Straitz et al., U.S. Pat. No. 4,139,339. As disclosed therein provisions are made for start-up, steady state or transient purged gas control and for failure of the purged gas supply. It also takes into account variable wind speed at or near the top of the stack, flow or non-flow of purge gas and waste gas in the stack. The patent also teaches provisions for ambient temperature and temperatures of the advancing gaseous medium in the stack, oxygen content of the gases, pilot burner gas supply and ignition with protection against pilot burner operation under undesirable conditions. A control panel is also provided so that an operator can take appropriate action when necessary.
A more recent approach to flare apparatus and methods are disclosed in the U.S. Pat. No. 5,846,068 of Schwartz et al. The Schwartz patent discloses an improved flare apparatus for burning flammable gas and air. The apparatus includes an outer tubular member and an inner tubular member positioned within the outer tubular member whereby an annular flammable gas discharge space is provided immediately adjacent to an annular air discharge space. The flammable gas is discharged into the atmosphere in an annular straight out pattern. At least a portion of the air is discharged into the atmosphere for mixing with the flammable gas in a swirling pattern immediately adjacent to the flammable gas which prevents internal burning and premature failure of the flare apparatus.
A further approach to burning stack gas is disclosed in a U.S. patent of Rajewski, U.S. Pat. No. 5,865,613. The Rajewski patent discloses a flare stack with a smokeless burn and reduced steam consumption. The flare stack includes a central pipe having a flare tip with a flare tip edge. An outer pipe surrounds the central pipe and forms an annulus between them. A spreader spreads gas from the central pipe into the annulus. Steam and air with oxygen are forced into the base of the annulus and past of the spreader to mingle with the gas and create smokeless burning. Steam and air are supplied by at least one conical conduit leading into the annulus, the conduit having an inlet for the flow of steam into it. A steam manifold having an outlet corresponding to each conduit, and each outlet being directed towards a corresponding inlet in the conduit are provided. In addition, an opening between each outlet and inlet for the flow of air into each conduit is drawn by a ventory effect.
Notwithstanding the above, it is presently believed that there is a need and a potential market for an improved apparatus for reducing pollution from a flare gas stack. There should be a demand for such apparatus since it will reduce pollution and reduce additional heat, acid rain and adverse effect on the ozone layer. In addition, the improved apparatus does not require burning of additional gases or added steam or oxygen to the flare gas. Further, it is presently believed that the apparatus in accordance with the present invention will have few moving parts and will be of durable construction.